Let's Talk About the Pelvic Floor
Childbirth is awesome and grueling. When a woman bears down for a single contraction, her uterine and abdominal muscles generate 25 pounds of pushing force. That’s enough to lift three gallons of milk, or two bowling balls, or even a car tire. As labor progresses, the muscles surrounding the vagina must stretch to three times their original length in order to accommodate the head of an average baby as it passes through the birth canal into the wider world.
“It’s an hour-and-a-half working, flat-out, as hard as you can,” says John DeLancey (M.D. 1977, Residency 1981), describing labor’s second stage. “And the interesting thing is: When somebody has done all of that and finally gotten the baby out, if there’s a pelvic floor injury, people say, ‘There, there; it’s going to be fine. It’s amazing how the body heals.’”
For most women, the body does heal in the weeks and months following a vaginal childbirth, but a startling 10 percent, or 300,000 women, incur a significant injury each year that causes long-term consequences. These may include incontinence, painful intercourse or prolapse — which occurs when an organ, such as the uterus or bladder, drops down through the vagina or rectum. Carmel Price, a 38-year-old mother of two and skilled runner, experienced some of these symptoms after the birth of her first child. Roughly six months after delivery, she resumed running, but during her menstrual cycle, her tampon would slide out of her body. In addition, she had two episodes of urinary incontinence, also while running. When she sought help from her obstetrician, she was told that “bodies change” after delivery. There was no conversation around the fact that childbirth can cause incontinence and pelvic organ prolapse. “In hindsight,” says Price, “I find that upsetting.”
Price’s symptoms worsened after the birth of her second child. “I had what they call a bulge,” she explains, referring to tissue that protrudes through the vaginal opening. “At first, I thought it was my uterus. Now I know it was my bladder.”
By that point, Price was in the midst of moving out of state and wasn’t able to attend a post-partum doctor’s appointment until two months after her delivery. Her new obstetrician correctly diagnosed bladder and rectal prolapse and referred her to physical therapy. When non-surgical interventions failed, she came to U-M for surgery. “As far as the surgery goes, it was successful, but I’m still trying to figure out my lifestyle,” states Price. She wants to remain physically active, but is concerned that she might reinjure herself with strenuous exercise.
Increasingly, women like Price are speaking out about the need for more awareness of pelvic floor disorders. Many people don’t realize, for example, that risk factors include gender (men do experience pelvic floor disorders, but at much lower rates), age, obesity and having given birth — particularly via vaginal delivery.
DeLancey, the Norman F. Miller Professor of Obstetrics and Gynecology, and a founder of the U-M Pelvic Floor Research Group, summarizes the situation: “Many women are saying, ‘Hey, wait a second, there are all these people who are having problems. Why isn’t anybody talking about this?’”
One way to answer that question is to consider how American culture views the pelvic floor: the grapefruit-sized region that includes the uterus, vagina, bladder and rectum, as well as the muscles, ligaments, connective tissues and nerves that support these organs. “It’s kind of a hush-hush part of the body,” says Ethel Potts, who had never heard of prolapse until her 80s, when she experienced it.
Many view this body region as personal and intimate. The downside is both women and men may lack the comfort — and even the vocabulary — to discuss their symptoms with a clinician. In particular, people often struggle to describe the sensation of prolapse: it isn’t pain, exactly, but pressure, or the feeling that things are out of place. A woman in clinic may say, “It feels like a tampon is in wrong,” or “When I sit down, I’m sitting on something.”
Until recently, this uncertainty regarding pelvic floor anatomy and function was common, even among health care workers. In the last three decades, however, medical knowledge has blossomed. In particular, U-M’s Pelvic Floor Research Group is recognized for its efforts to elucidate the biomechanics of the area and use this knowledge toward prevention and treatment. Today, the group includes approximately 40 researchers from disciplines as diverse as medicine, biomechanical engineering, nursing, epidemiology and anthropology. But it began with just three people.
In the 1980s, U-M received the cadaver of a young woman who had died of cancer. Young specimens are so rare that James Ashton-Miller, Ph.D., a professor in the College of Engineering, had been waiting two years for a donation so that he could study a young person’s spine. Upon hearing of its arrival, he called the Anatomical Donation Program.
“The guy said, ‘It’s gone,’” recalls Ashton-Miller, the Albert Schultz Collegiate Research Professor and distinguished research scientist of mechanical engineering, of biomedical engineering, of internal medicine, of kinesiology, and the associate vice president of research policy and compliance. The specimen had been given to a physician in the Department of Obstetrics and Gynecology — John DeLancey.
Ashton-Miller phoned DeLancey, and the two agreed to share the cadaver. At the time, DeLancey was studying bladder control in young women. He had done biomechanics research as an undergraduate and was interested in extending that line of research to the pelvic floor, but no one he had contacted on campus was interested. As it happens, Ashton-Miller was interested in using biomechanics to better prevent unintentional injuries. He also had a latent interest in incontinence — his father was a urologist. The two men met for coffee to discuss collaboration, and were soon joined by a graduate student, Janis Miller, Ph.D., R.N., who had decided to study incontinence after working in nursing homes.
“We had a zillion questions that nobody knew how to answer,” recalls DeLancey.
Initially, the group focused on urethral function. When they realized that some problems with the urethra had their origins in childbirth, the group decided to extend its focus to the biomechanics of labor and delivery. “If you know when, where and why the injuries occur,” says Ashton-Miller, “then you might be able to better prevent them.”
The team wanted to figure out which part of the pelvic floor undergoes the greatest stretch during childbirth because that part would presumably be at greatest risk for injury. Ashton-Miller and his graduate students did some computer modeling, and in the early 2000s, they developed what would become known as the bowling ball model. “It was the simplest possible model we could think of at the time,” says Ashton-Miller, explaining that when looking at a complicated phenomenon like birth, it helps to start with a simple model. In this case, the team modeled the baby’s head as a sphere, hence the bowling ball analogy.
The model did make a prediction: a particular set of muscles, referred to collectively as the levator ani, are most at risk during vaginal childbirth. The levator ani is a broad, thin muscle situated on each side of the pelvis.
It surrounds the anal canal, the urogenital hiatus, the vagina in females, and the prostate in males. Would an injury in this region cause incontinence, prolapse or other types of pelvic floor dysfunction?
It was the right time to ask this question. In the 1980s, researchers had begun using MRIs to study the pelvic floor, revolutionizing the field. “Before MRIs, we had no accurate measure of the dimensions or orientations of the structures in the pelvic floor,” says Ashton-Miller. X-rays don’t allow one to study soft tissues in enough detail, and at the time, ultrasounds were grainy. Researchers hoping to visualize the pelvic floor had to rely on cadavers. But a cadaver doesn’t exhibit muscle tone, so its pelvic floor is shaped differently than in a living person.
Using MRIs, DeLancey, Ashton-Miller, Miller and their colleagues were able to determine that prolapse does indeed result from a levator ani tear and that this tear can occur during childbirth. Normally, the levator ani muscles support the pelvic floor organs, but when those muscles are damaged, the organs lose their physical support and begin to droop. A young woman who injures her levator muscle may experience symptoms immediately, as Carmel Price did. Others, however, don’t develop symptoms until later in life with age-related muscle loss. This was the case for Ethel Potts, when she experienced a prolapsed uterus.
Potts’ general practitioner correctly diagnosed her. Because Potts was reluctant to have surgery, she initially used a pessary — a removable device that a physician or patient can place in the vagina in order to hold the pelvic organs in position. Eventually, however, Potts’ condition worsened and the pessary no longer worked. She had surgery at U-M in 2013. “It was remarkable,” she says, describing the outcome. “My body — the way it felt, the way it looked — was exactly as it had been when I was young. It was as though I had never been through childbirth, pregnancy, or prolapse.”
Despite the positive results, Potts still wonders what caused her prolapse. At this point, no one can say definitively why some women are injured during childbirth, but U-M researchers suspect that the size of a woman’s birth canal — and the size of the baby’s head — are relevant.
Potts has two children and describes the first birth as “not standard” because it took so long and she only felt labor pains in her back. “I’m small and my babies were both born with flattened foreheads,” she recalls. “Their skulls were pushed way in from the eyebrows up. … And they were both a week overdue.”
In 2015, Ashton-Miller, DeLancey and Paige Tracy, a graduate student in the Department of Biomedical Engineering, returned to the original bowling ball model of childbirth. They refined the model so that it could analyze the relationship between the size of a woman’s birth canal and the size of a baby’s head in order to determine which women are at risk of incurring injury during a vaginal delivery.
Their results, published in the Journal of Biomechanical Engineering, suggest that roughly 75 percent of women can give birth to any size baby without injury. More troubling, the results suggest that women in the bottom 10 percent of birth canal size risk injury delivering a baby “for all head sizes.” The researchers’ next step will be to validate their theoretical predictions against actual birth outcomes. Ultimately, the goal is to be able to provide a pregnant woman and her clinician with an assessment of her birth canal size relative to the size of her baby’s head. This would allow her to make a more informed decision about whether she might, for instance, choose a Caesarean section.
Carmel Price delivered her first baby in a birthing center with nurse midwives who supported her choice to forgo an epidural and deliver vaginally. Price’s preference for a vaginal delivery reflects the view of the American Congress of Obstetricians and Gynecologists, which recommends against C-sections unless they are medically necessary. While the number of C-sections has doubled in the last decade — accounting for nearly 1 in 3 births in the United States — the procedure does have drawbacks, including increased risk of respiratory problems for the infant and greater complications for the mother’s subsequent pregnancies.
Ultimately, the computer modeling may provide women with additional information, helping them to prepare for childbirth. Says Price, “In hindsight, if I had had any information about pelvic floor injuries prior to childbirth — if I had known I was at risk of pelvic organ prolapse, something I now have to manage for the rest of my life — if I could have prevented that with a C-section, knowing what I know now, that would be fantastic.”
Healthy Healing After Delivery
In 2007, U-M opened the Healthy Healing After Delivery Program, a first-of-its-kind clinic where pelvic floor research is put into action. The program provides support to women who need specialized and comprehensive care following delivery. This includes women with third- and fourth-degree lacerations, urinary and fecal incontinence, and pain from pelvic floor muscle spasm.
“We try to look at pelvic floor issues from all perspectives,” says Dee Fenner, M.D. (Residency 1989), the program’s director, the Harold A. Furlong Professor of Women’s Health in the Department of Obstetrics and Gynecology, and director of the Division of Gynecology. Patients at the clinic see nurses and a physician. Depending on their condition, they may also work with a physical therapist.
“Education is a real cornerstone of the program,” says Fenner. She believes most woman are told about their injuries while still in the hospital, “but if you don’t know what a third-degree or a fourth-degree [laceration] is, it doesn’t mean anything to you. And you’re exhausted; you may have been through hours of labor. You have a new baby; you may have some anesthetic on board. There are a lot of things going on. So when they come to the clinic, a lot of women have questions: ‘How often does this happen? Is it going to happen again? What can I do to make it heal better?’”
Many conditions can be resolved with physical therapy rather than surgery. Jennifer Shifferd, a pelvic floor physical therapist who sees clinic patients, explains that the first goal is to help patients locate their pelvic floor musculature. From there, she helps the patient begin a strengthening program which may include a variety of exercises including Kegels. Some women also experience painful muscle spasms following delivery and hypersensitivity as their scar tissue is healing. In this case, Shifferd can do very gentle muscle releases from inside or outside the pelvic floor area as well as scar tissue massage. Education is key for the patient to have success with their home program.
One patient named Sarah (who requested we not use her last name) came to the clinic and saw Fenner after delivering her first child because she was having difficulty urinating. “The whole team there explained their experience with this condition and gave me some reassurance that it would take time, but it would heal,” says Sarah. In the meantime, they provided her with catheters that allowed her to continue working and prescribed medication for her urinary tract infections. Fenner also discovered that Sarah had a small prolapse and referred her to physical therapy. Now, Sarah is pregnant with her second child.
“They have discussed some of the limits I need to set so that I don’t injure myself again. I’m only supposed to push for about an hour and I have worked with a midwife to discuss the problem.”
Patients have much to gain from speaking about pelvic floor dysfunction with their health care team. The body doesn’t always heal properly following childbirth, but tools are available to manage and sometimes even resolve conditions like incontinence and prolapse. For her part, Carmel Price describes herself as “incredibly thankful and grateful” for the care she received at U-M. “I’m trying to do my part by discussing my experiences openly,” she says. “We have to eliminate the taboo and shame women feel around pelvic floor dysfunction.”